The existing fringe projection technique is only adapted for diffusive objects. For specular objects complying with the law of reflection, only a part of the surface with the fringes can be observed. Reflected light from other regions cannot project to the image capture system, resulting in deletion of part of the image data. On the other hand, the reflected light which projects to the image capture system has an exorbitantly high light intensity, so as to form an image with a saturation greyscale value, and further to make the fringe image too bright or form a bad contrast ratio.
Therefore, it is necessary to provide a method for measuring a specular object by fringe projection to solve the above described problems.